Automatic throttle torque-responsive power tool



D. W. TIBBOTT AUTOMATIC THROTTLE TORQUE-RESPONSIVE POWER TOOL Filed June12, 1968 q 65 so If 47 I 6 44 0 43 ,55 48 I Q J. f, 4 5a 3 Sheets-Sheet2 FIG. 6

|NVENTOR DAV/D W 7736077 BY 7 3M w- 'M ATTORNEY May 19, v1970 D. W.TIBBOTT 3 Sheets-Sheet 5 Filed Jline 12, 1968 3 O 9 v. w n n 4 0 H/. kIi. w i a F a 3 8 w n w m 0 4 7. 9 3 3 3 w m w 5 T 9 4 H \\\\\\\\\\\v .H

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United States Patent 3,512,590 AUTOMATIC THROTTLE TORQUE-RESPONSIVEPOWER TOOL David W. Tibbott, Phillipsburg, N.J., assignor toIngersollgland Company, New York, N.Y., a corporation of New ersey FiledJune 12, 1968, Ser. No. 736,343 Int. Cl. B25b 23/14 US. Cl. 17312 14Claims ABSTRACT OF THE DISCLOSURE A fluid-operated rotary power toolhaving a motor supply valve seat which is moved into engagement with thevalve in response to a clutch reaching a predetermined torque load,thereby closing the valve and stopping the motor. The movable valve seatis normally latched against movement and the torque responsive clutchreleases the latch upon reaching the predetermined torque.

BACKGROUND OF INVENTION This invention relates to the art ofpower-operated rotary tools such as power screwdrivers and powerwrenches.

It is conventional in the power tool art to provide a power wrench orscrewdriver with a torque-responsive clutch which automatically releasesthe tool spindle from its motor when the torque load rises to a selectedmagnitude. It is also conventional in the air of fluid-operated powertool art to interconnect the torque-responsive clutch to the supplyvalve for the motor by a means that causes the valve to shut when theclutch releases. Prior tools accomplishing the above result have used atelescoping connection between the clutch and the valve and thisconnection is allowed to collapse when the clutch opens resulting inallowing the valve to close and stop the motor.

SUMMARY OF INVENTION The principal object of this invention is toprovide a new type of mechanism which accomplishes the above results andeliminates the telescoping connection between the clutch and the valve.

Other important objects of this invention are: to provide a novel supplyvalve for a power tool; to provide a simplified shut-off mechanism foran air-operated power tool; and to provide a valve having one movableelement for opening the valve and another movable element for closingthe valve.

In general, the foregoing objects are provided by a rotary tool having asupply valve which is opened by the operator to start the motor and amovable valve seat which is latched in a normally stationary position tostop it from following the valve as it moves -to its open position.Means is provided for the tool to measure the torque load on the tooland, in response to a predetermined torque load, to unlatch the movablevalve seat whereby the valve seat moves into engagement with the valveto close the valve and to stop the motor. Thereafter, the operatorallows the valve to return to its normally closed position. In returningto its normally closed position, the valve will carry the movable valveseat with it to its normally latched position.

BRIEF DESCRIPTION OF DRAWINGS The invention is described in connectionwith the accompanying drawings wherein:

FIG. 1 is a longitudinal section of an air-operated power screwdriveremploying a torque-responsive shutoff mechanism following the principlesof this invention;

FIG. 2 is a section taken on line 22 in FIG. 1;

Patented May 19, 1970 FIG. 3 is a fragmentary section taken on line 33in FIG. 1;

FIG. 4 is a fragment of FIG. 1 illustrating the air supply valve of thetool motor in its open position;

FIG. 5 is a view similar to FIG. 4 illustrating the valve mechanismimmediately following the rearward movement of the valve seat to itsengaged position with the valve to shut off air flow to the tool motor;

FIG. 6 is a longitudinal section of an air-powered angle wrench usingthe mechanism of this invention and illustrating the valve in itsnormally seated and closed position;

FIG. 7 is a fragment of FIG. 6 illustrating the valve in its openposition;

FIG. 8 is a view similar to FIG. 7 illustrating the valve mechanismfollowing the rearward movement of the valve seat to its engagement withthe valve to shut off air flow to the tool motor;

FIG. 9 is a fragmentary vertical section of a third embodiment showing ascrewdriver valve mechanism having the latch mechanism carried on thevalve seat sleeve;

FIG. 10 is a fragmentary vertical section of a fourth embodiment showinga screwdriver valve mechanism having a ball latch; and

FIG. 11 is a fragmentary vertical section of a fifth embodiment showinga screwdriver valve mechanism having a pilot-operated valve.

DESCRIPTION OF I HE PREFERRED EMBODIMENTS The power-operated screwdriver1 shown in FIGS. 1 to 5 includes a casing 2 housing an air motor 3having a drive shaft 4. The screwdriver 1 has an air hose fitting 5threaded into the rear end of the casing 2 for coupling to an air hose(not shown) for feeding air to the tool. The front nose 6 of thescrewdriver 1 carries a screw finder 7 and a screwdriving blade 8adapted to engage the slot of a screw. The blade 8 i detachably mountedin a spindle 9 which is rotatably and slidably mounted in a journalbearing 10 integrally formed in the interior of the casing. The bearing10 carries a rearwardly facing shoulder '11 which engages a portion ofthe spindle 9 to limit its forward movement. The motor drive shaft 4 ismounted in the bearing 12. All of the foregoing structure isconventional in the screwdriver art.

The spindle 9 is interconnected to the motor drive shaft 4 by a torqueresponsive clutch mechanism 14 which releases under a predeterminedtorque load. The clutch mechanism 14 includes a hollow clutch shaft 15having its rear end slidably splined in a socket 16 formed in the motordrive shaft 14, thus allowing the clutch shaft 15 to slide rearwardlyinto the socket 16 for a limited distance while maintaining a continuousdriving connection therebetween.

The front end of the clutch shaft 15 is attached to the spindle 9 by aconnection which allows the clutch shaft 15 to rotate relative theretowhile being unable to slide axially relative to the spindle 9. Thisconnection is formed by the front end of the clutch shaft 15 beingseated in a rearwardly-opening bore 17 provided in the spindle 9 withseveral balls 18 being located in mating annular grooves formed in theclutch shaft 15 and the interior wall of the bore 17.

The clutch shaft 15 is urged forwardly by a light spring 20 engagedbetween the bearing 12 mounting the drive shaft 4 and a washer 22resting on a rearwardly facing shoulder formed on the clutch shaft 15.As a result, the light spring 20 biases the spindle 9 against theshoulder 11 of the bearing 10. The clutch shaft 15 and spindle 9 aremoved rearwardly in the tool by an operator forcing the tool blade 8downwardly against a screw. The depth of the socket 16 in the driveshaft 14 limits the rearward movement of the clutch shaft 15.

The clutch shaft 15 carries an integral clutch plate 24 which contains aseries of holes spaced around its center. These holes housecorresponding clutch balls 25 adapted to seat in mating ball seats orrecesses provided in the rear face of the spindle 9. The balls 25 arepressed into their seats in the spindle 9 by a presser ring 26 which isurged forward by a clutch spring 27. The rear end of the clutch spring27 seats against a collar 28 which is keyed on the clutch shaft 15 andis held in place by a nut 29 threaded on the clutch shaft 15. A detentball 30 is located in the rear face of the collar for seating in any ofa series of cavities in the front face of the nut 29 to latch the nut 29in its adjusted position. The nut 29 includes 'gear teeth 31 on itsperiphery for engaging with a Jacobs chuck key (not shown) to aid inturning the nut 29 to adjust the load on the clutch spring 27. The loadon the clutch spring 27 will determine the magnitude of torque load atwhich the torque clutch 14 will release.

The presser ring 26 engages a cross bar 32 which slides in a diametricalslot 33 formed in the clutch shaft 15 and abuts the forward end of apush-rod 34 which extends rearwardly from the cross bar 32 through thehollow clutch shaft 15 and the drive shaft 4 of the motor 3. As a resultof the foregoing arrangement, the disengagement of the clutch undertorque will move the presser ring 26 rearwardly on the clutch shaftresulting in moving the push-rod 34 rearward.

The air fitting extending from the rear end of the casing 2 opens into avalve chamber 36 housing a valve 37 resting on a stationary valve seat38. The valve 37 is attached to the rear end of the push-rod 34 andcloses the top end of a valve bore 39. The valve bore 39 is connected toa motor supply passage 40 extending to the tool motor 3. The valve 37controls the flow of air from the valve chamber 36 to the motor 3 viathe bore 39 and the motor supply passage 40.

When the screwdriver is initially pressed downwardly on a screw, thespindle 9, the clutch shaft 15, push-rod 34 and valve 37 move rearwardlyin the tool to raise the valve 37 above the stationary valve seat 38, asshown in FIG. 4, and allow air to flow through the motor supply passage40 to the motor 3. This air will drive the motor 3 and the screwdriverwill drive the screw engaged by the blade 8.

As the screw is driven home, it will become tight and the torque load onthe spindle 9 will rise until it reaches the predetermined torque loadthat will cause the clutch mechanism 14 to release and slip. The releaseof the clutch mechanism 14 is caused by the clutch balls 25 rolling outof their seats or pockets on the rear end of the spindle 9 and thisunseating movement of the clutch balls 25 forces the push-rod 34 andvalve 37 further rearwardly in the tool. This additional rearwardmovement releases a movable valve seat sleeve 42 which is slidablymounted in the valve bore 39. A spring 43 urges the sleeve 42 rearwardlyin the valve bore 39 so that the release of the valve seat sleeve 42allows it to move rearward into engagement with the valve 37. Theengagement of the valve seat sleeve 42 with the valve 37 closes the flowof air from the valve chamber 36 to the motor 3.

The latch mechanism for the valve seat sleeve 42 includes a pivotedlatch 44 having a tongue 45 adapted to engage an annular groove 46provided in the periphery of the valve seat sleeve 42. The tongue 45 isbeveled on its top. A light spring 47 urges the latch tongue 45 into thegroove 46. The latch includes a release arm 48 projecting into the pathof an enlarged abutment 49' on the push-rod 34 and located so that theadditional rearward movement of the push-rod 34, in response to therelease of the clutch mechanism 14, will engage the release arm 48 androtate the latch 44 to release the latch tongue 45 from the annulargroove 46 in the valve seat sleeve 42. As soon as e the va ve seatsleeve 42 is released, it is moved upward by the spring 43 to engage thevalve 37, thereby stopping the flow of air from the valve chamber 36 tothe motor 3, as shown in FIG. 5. As a result, the motor 3 is stopped.Thereafter, the operator lifts the screwdriver 1 from the screw, thusallowing the spindle 9 to move forward to seat on the bearing shoulder11. This movement allows the push-rod 34 and valve 37 to move forwarduntil the valve 37 is again seated on the stationary valve seat 38. Theforward movement of the valve 37 carries the valve seat sleeve 42forwardly with it and the latch tongue returns to a latched position inthe annular groove 46. The screwdriver 1 is now in the condition asshown in FIG. 1. At this time the screwdriver is ready for anothercycle.

SECOND EMBODIMENT The second embodiment is an angle wrench 54illustrated in FIGS. 6 to 8. The angle wrench 54 includes a casing 55having an air hose fitting 56 fixed to its rear end and a socket arbor57 projecting from its front end at right angles to its length. Thewrench 54 contains a motor 58 and a throttle button 59 adapted to bepressed to feed air to the motor 58. All of the foregoing structure isconventional in the power wrench art.

In describing the novel structure in the angle wrench 54, elements whichare similar or identical to those found in the first embodiment willcarry identical reference numbers.

The torque responsive clutch mechanism 14 used in the second embodiment54 is identical to the clutch mechanism 14 of the first embodimentexcept that the clutch shaft 15 cannot move rearwardly for a shortdistance. In brief, the spindle 9 drives the socket arbor 57 and isengaged by clutch balls 25 housed in a clutch plate 24 mounted on theclutch shaft 15. At a predetermined torque, the clutch balls 25 rise outof seats on the spindle 9 to move the presser ring 26 rearward. Therearward movement of the presser ring 26 acts through a cross bar 32 tomove a push-rod 34 rearward.

The throttle button 59' operates a pilot-operated throttle mechanism.The air hose fitting 56 opens into a passage 60 extending to the forwardend of a cylindrical valve bore 61. The cylindrical bore 61 contains aslidable valve seat sleeve 42 and a slidable spool valve 63 adapted toseat on the valve seat sleeve 42 to stop air in the bore 61 fromentering a motor supply passage 64. The spool valve 63 is urged againstthe valve seat sleeve 42 by a spring 65. The spool valve 63 contains asmall longitudinal vent 66 extending between its opposite ends. The endportion of the bore, rearwardly from the spool, is termed a pilotchamber 67. The throttle button 59 is connected to the pilot chamber 67so that depression of the throttle button 59 will exhaust air pressurefrom the pilot chamber 67. The exhausting of the pilot chamber 67creates a differential in pressure across the spool valve 63 to causethe valve 63 to move rearwardly to its open position as shown in FIG. 7.The spool valve 63 will remain in the open position as long as thethrottle button 59 is depressed. At this time the tool motor 58 will berunning and the arbor 57 is normally driving a fastener.

In the event the operator wishes to stop the wrench 54 before thefastener is driven to a selected torque load, the throttle button 59 isallowed to return to its raised position, the vent 66 will allow thedifferential of pressures across the spool valve 63 to return to abalanced condition and the spring will return the spool valve 63 to itsclosed position, as shown in FIG. 6.

The valve seat sleeve 42 of the second embodiment 54 is slidable in thevalve bore 61 in the same way that the valve seat sleeve 42 is slidablein the valve bore 39 in the first embodiment. In addition, the valveseat sleeve 42 is urged rearwardly by a spring 43 and held in itsforward position by a latch 44 having a tongue 45 engaging in an annulargroove 46 provided in the circumference of the valve seat sleeve 42.

This latch mechanism is identical to the latch mechanism of the firstembodiment with the exception that the rear end of the push-rod 34 isadapated to engage the release arm 48 of the latch 44 when the clutchmechanism 14 begins releasing or slipping at the predetermined torqueload. When the latch 44 is released by the push-rod 34 at predeterminedtorque, the valve seat sleeve 42 moves rearwardly into engagement withthe spool valve 63 to seal 01f air from the motor passage 64, as shownin FIG. -8, thus stopping the tool motor 58 in the same manner as inthefirst embodiment.

Thereafter, the operator releases the throttle button 59 to again sealthe pilot chamber 67 whereby the dilferential of pressure across thespool valve 63 is returned to a balanced condition and the spring 65forces the spool valve 63 to return to its forward closed position asshown in FIG. 6, while carrying the valve seat sleeve 42 forward withthe spool valve 63. In order for the spring 65 to accomplish thisresult, it is stronger than the valve seat sleeve spring 43. The wrench54 is now in condition for another cycle.

THIRD EMBODIMENT The movable valve seat 42 can be latched in its forwardposition by various other forms of latches than that shown in thedrawings. One example of this is shown in FIG. 9 and contains a latchdetent 69 pivoted in a longitudinal slot 70 in the side Wall of thevalve seat sleeve 42 and adapted to engage an annular groove 71 formedin the wall of the bore 39 holding the latch detent. The lower end ofthe latch detent 69 carries a cam ramp 72 adapted to cooperate with acam cone 73 fixed on the push-rod 34 to disengage the latch detent 69when the push-rod 34 rises in response to the tool reaching thepredetermined torque load. The tool shown in FIG. 9 is a screwdriver andmay contain the same clutch mechanism 14 as that shown in FIG. 1.

FOURTH EMBODIMENT The fourth embodiment shown in FIG. contains aball-type latch for the valve seat sleeve 42. The valve seat sleevecontains an annular groove 75 adapted to receive a latch ball 76 whichis housed in a hole provided in a thin section 77 of the Wallsurrounding the bore 39. A latch bar 78 is slidably mounted behind thethin section 77 and contains a ball recess 79 adapted to receive thelatch ball 76 when the latch bar 78 is raised from the position shown inFIG. 10. A spring 80 engages the top of the latch bar 78 to urge itdownwardly. The latch bar 78 contains an arm 81 projecting inward overthe abutment 49 for engaging it. The latch bar 78 is lifted by thepush-rod 34, during its additional rearward movement, when the toolreaches the predetermined torque load. The upward movement of the latchbar 78 moves the ball seat 79 adjacent to the ball 76 whereby the ballcan move into the ball seat 79 and release the valve seat sleeve 42.

FIFTH EMBODIMENT The fifth embodiment shown in FIG. 11 illustrates theuse of the invention in connection with a pilot-operated valve in ascrewdriver. A valve seat sleeve 84 is slidably mounted in a bore 85provided in the tool body and contains an internal flange 86 projectinginward in the upper portion of the sleeve 84. The flange 86 contains acentral opening 87. In addition, the valve seat sleeve 84 containsseveral ports 88 extending through its sides and adapted to carry airflow to the motor passage 40.

A pilot-operated valve spool 90 is slidably mounted in the lower end ofthe valve seat sleeve 84 and is adapted to engage the flange 86 to sealthe flow of air to the motor passage 40. The top of the spool valve 90contains a resilient pad 91 to aid the sealing action of the valve 90. Aspring 92 urges the spool valve 90 toward its closed position.

The spool valve 90 contains a small axial passage 93 which allows theair pressure acting on the top of the valve to flow into a pilot chamber94 located under the valve 90, thereby balancing the pressure across thevalve. Normally, the pressure in the pilot chamber 94 is closed by asmall pilot valve 95 attached to the top of the push rod 34. A latchcrank 96 is pivoted in the pilot chamber 94 and has a portion adapted toengage a recess in the side wall of the valve seat sleeve 84, thuspreventing it from moving downwardly until unlatched.

The pilot valve 95 contains a diametrical opening 97 receiving one armof the latch crank 96. The opening 97 is large enough to allow the pilotvalve 95 to open during the initial movement of the push-rod 34 withoutreleasing the latch crank 96. As soon as the pilot valve 95 opens, thepilot chamber 94 is vented and the resulting pressure differentialacting on the spool valve 90 opens it. Thereafter, when the tool reachesits predetermined torque load, the push rod 34 moves upwardly anadditional distance to release the latch crank 96 and allow the valveseat sleeve 84 to move downwardly, due to the differential of pressureacross it. Thus, the valve seat sleeve 84 will seat On the spool valve90 and stop the flow of air to the motor.

Both the spool valve 90 and the valve seat sleeve 84 will return totheir upper positions when the pilot valve 95 is closed, as a result ofthe force provided by the spring 92.

Although five embodiments of the invention are illustrated and describedin detail, it will be understood that the invention is not limitedsimply to these embodiments, but contemplates other embodiments andvariations which utilize the concepts and teachings of this invention.

I claim:

1. A fluid-operated rotary power tool comprising a casing;

a fluid motor driving a spindle;

a valve controlling the flow of motive fluid to said motor and movablein one direction from a closed position to an open position to startsaid motor;

a torque sensing means connected to said spindle to measure apredetermined load on said spindle and to create a signal; and

a member movably mounted on said casing and operative to receive saidsignal and move in response to said signal, to engage said valve in itsopen position to shut off the flow of motive fluid to said motor.

2. A fluid-operated rotary tool comprising:

a housing including a fluid-operated rotary motor;

a valve controlling the flow of motive fluid to said motor and movablefrom a closed position to an open position wherein motive fluid flows tosaid motor;

a valve seat normally disengaged from said valve in its open positionand movable to engage said valve in said open position to shut olf theflow of motive fluid to said motor; and

torque sensing means connected to said motor to measure the torque onsaid motor and being operative, in response to a predetermined torqueload on said motor, to eifect the movement of said valve seat to itsengagement position with said valve.

3. The rotary tool of claim 2 including:

a rod interconnecting said torque sensing means with said valve seat.

4. The rotary tool of claim 2 including:

latch means locking said valve seat in a position normally disengagedfrom said valve in its open position and operative to release said valveseat when said torque sensing means reaches said predetermined torque;and

means urging said valve seat toward its engaged position with saidvalve.

5. The rotary tool of claim 4 wherein: said torque sensing means is atorque-responsive clutch connected to a rod extending towards said valveseat and operative to move said rod toward said valve seat when saidclutch reaches said predetermined torque.

6. The rotary tool of claim 5 wherein:

said latch means includes a movable element adapted to engage a latchsurface provided on said valve seat.

7. The rotary tool of claim 4 wherein:

said valve is engaged by said push-rod and is moved to an open positionby the operator pressing the tool against a workpiece.

8. The rotary tool of claim 4 wherein:

said valve is movable to its open position by the operation of athrottle member by an operator.

9. The rotary tool of claim 4 wherein:

said latch means includes a movable element mounted on said valve seat.

10. The rotary tool of claim 4 wherein:

said valve is a pilot-operated valve.

11. The rotary tool of claim 10 wherein:

said pilot-operated valve is movably mounted within said valve seat.

12. A fluid-operated rotary tool including:

a fluid-operated motor; and

valve means including a first portion movable from a first position,wherein it shuts off the flow of motive fluid to said motor, to a secondposition, wherein it allows motive fluid to flow to said motor, and asecond portion movable from a third position to a fourth position,wherein it engages with said first portion when in said second positionto shut off the flow of motive fluid to said motor.

13. The rotary tool of claim 12 including:

means operable by an operator for moving said first portion of saidvalve means to said second position; and

other means operative, in response to a predetermined torque load on thetool, to move said second portion of said valve means to said fourthposition.

14. A fluid-operated rotary tool comprising:

a housing including a fluid-operated rotary motor;

a spindle movable rearwardly in said housing;

valve means controlling the flow of motive fluid to said motor andmovable rearwardly in said housing over a distance including first andsecond successive increments of travel, said valve means being movablerearwardly over said first increment of travel from a closed to an openposition and movable rearwardly over said second increment of travelfrom an open to a closed position;

means interconnecting said spindle to said valve means to transmit therearward movement of the spindle to the valve means for moving saidvalve means over said first increment of travel thereby to open saidvalve means; and

torque sensing means connected to said motor to measure the torque onsaid motor and being operative, in response to the rise of the torqueload to a predetermined torque load, to cause said valve means to moveover said second increment of its travel, thereby to close said valvemeans.

References Cited UNITED STATES PATENTS 3,059,620 10/1962 Eckman 17312 X3,082,742 3/1963 Vicmerding et a1. 81-52.4 3,162,250 12/1964 Sindelar173-12 3,242,996 3/1966 Wright et a1 173--12 X 3,385,377 5/1968 Amtsberget a1 173-12 ERNEST R. PURSER, Primary Examiner US. Cl. X.R.

